Method for coating stainless steel press plates and coated press plates produced thereby

ABSTRACT

A method for coating stainless steel press plates includes preparing the stainless steel press plate for coating and coating the stainless steel press plate with a diboride doped with 1%-5% by weight aluminum to produce a diboride-aluminum coating. The step of coating includes applying the diboride-aluminum coating to a stainless steel press plate using a magnetron sputter coating system.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application Ser.No. 62/293,032, entitled “METHOD FOR COATING STAINLESS STEEL PRESSPLATES AND COATED PRESS PLATES PRODUCED THEREBY,” filed Feb. 9, 2016.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to coated, abrasion resistant press plates usedin making abrasion resistant decorative laminate, coating of pressplates and making laminate with these press plates. Grit, e.g., aluminaparticles, on the pressing surface of abrasion resistant decorativelaminate can scratch press plates and reduce the visual quality oflaminate thereafter made with the press plate. Press plates of thisinvention are particularly useful in making abrasion resistant highgloss decorative laminate.

2. Description of the Related Art

In the manufacture of decorative laminate, layers of resin impregnatedpaper are pressed against press plates under conditions of temperatureand pressure to cure the resin and bond the layers together. A highgloss press plate imparts a high gloss surface to laminate. A pressplate with a textured surface will impart a textured surface tolaminate. These press plates are extremely uniform, with evenmicroscopic discontinuities being minimized. The quality of a high glosspolished press plate can be determined by viewing reflected images onits surface and scrutinizing the reflected images for opticaldiscrepancies. Grit is often applied to laminates in an effort toimprove wear characteristics. The grit on the surface of laminate causesmicro scratching of stainless steel press plates normally used in themanufacture of decorative laminate, thus destroying the micro finish ofthe press plate. Press plates can also be scratched by press platehandling equipment and by debris from pressing equipment or materialsused in making laminate. See Laurence U.S. Pat. No. 5,244,375.

Melamine resin coated decorative laminates are pressed at temperaturesof about 230° F.-310° F. (110° C.-155° C.) and pressures of about300-2000 psi (20-136 bar) and preferably about 750-1500 psi (51-102bar). Heating to these temperatures and cooling to room temperatureresults in substantial expansion and contraction of the laminate and ofthe press plate. Expansion and contraction of the laminate and pressplate will not be the same, resulting in the movement of grit on thepressing surface of laminate across the press plate.

It is disclosed in National Electrical Manufacturers Association (NEMA)Standards Publication No. LD 3, that gloss finish laminate has a glossof 70-100+. High gloss textured finish laminate is disclosed as having agloss of 21-40. Black glass with a gloss of 94+1, measured at an angleof 60 degrees, is disclosed as the NEMA Standard 3.2.2, for calibratinga gloss meter for 60 degree angle gloss measurements.

Even discontinuities in high gloss press plates that can only be seenwith a microscope can impart visible surface defects to a high glosssurface of laminate. Any scratching of high gloss press plates impartsvisible surface defects to high gloss surfaces of laminate and reducesgloss level.

Grit on the decorative surface of laminate imparts abrasion resistance,a commercially desirable characteristic of laminate. Particles ofalumina are commonly used as grit in making decorative laminate. TheVickers hardness of alumina is disclosed in “Tribology: Friction andwear of Engineering Materials”, I. M. Hutchings, CRC Press, 1992, to be1800 HV (Vickers Pyramid Number) to 2000 HV. A useful range of particlesizes is about 10 microns to about 75 microns. Grit of about 25 micronsto 60 microns is preferred. Optimum abrasion resistance is obtained inthe particle size range of about 40 microns to 60 microns. See Lane etal. U.S. Pat. No. 3,798,111.

Alumina having a maximum particle size of 9 microns is disclosed asbeing effective for imparting a wear resistant surface to glossydecorative laminate. Wear resistance is defined as the resistance of aglossy laminate to loss of gloss when the surface of laminate is exposedto the abrasive effects of sliding objects. It is acknowledged that theresulting laminate does not meet NEMA LD 3.13 requirements to beconsidered as abrasion resistant. However, it is disclosed that glossypress plates are not scratched substantially if the grit particle sizeis maintained at less than 9 microns. See Lex et al. U.S. Pat. No.4,971,855.

The use of a 410 stainless steel press plate hardened by nitriding isdisclosed for making high gloss decorative laminate. After pressing 100sheets of high gloss laminate with 6 micron grit and 15 micron grit, thegloss of the pressed laminate remained good to very good. The nitridedpress plate exposed to the 6 micron grit was rebuffed after 234 cyclesand produced acceptable laminate quality for at least another 103cycles. Nitrided press plates exposed to 30 micron grit offered limiteddurability. It is disclosed that the 410 stainless steel press plateused for nitrating had a Rockwell, “C” scale hardness of 38-45 and thatthe nitrided surface had a Rockwell, “C” scale hardness of 60-70. Theequivalent Vickers hardness of 410 stainless steel is about 370-440 HV,based on a conversion table published in “Metals Handbook, MechanicalTesting”, Vol 8, 9th ed., ASM, 1985. The equivalent Vickers hardness ofnitrided 410 stainless steel is about 500-1000 HV, based on a conversiontable published in “Metals Handbook, Mechanical Testing”, Vol. 8, 9thed., ASM, 1985. See Laurence U.S. Pat. No. 5,244,375.

Laminate with alumina at its surface has been pressed with high glosspress plates coated with titanium nitride. After ten pressings, thetitanium nitride coated press plates had about 15 scratches per squarecentimeter. A control 410 stainless steel press plate had about 500scratches per square centimeter.

The control press plate and the press plate on which the titaniumnitride was coated were cut from the same stainless steel pressingplate. The scratches were visible under a light microscope at 40×magnification. Titanium nitride was coated onto 410 stainless steel highgloss press plates in a magnetron sputter coating system.

There is a need for a hard coating on press plates, continuous belts,and other pressing surfaces that imparts a color to laminate having anASTM D 2244 color difference in comparison to a standard of less than(±0.5) ΔE. There is a need for a coating that can be applied to pressingsurfaces without changing the appearance of the finish on the pressingsurface. There is a need for pressing surfaces that are not scratchedwhen used in pressing laminate coated with alumina particles of greaterthan 10 microns and preferably greater than 25 microns. There is aparticular need for pressing surfaces that are not scratched when usedin the manufacture of high gloss laminate with an ASTM 2457 60 degreeangle gloss of greater than 70, when the surface of the laminate iscoated with 25-60 micron alumina particles.

SUMMARY OF THE INVENTION

It is, therefore, an object of the present invention to provide a methodfor coating stainless steel press plates. The method includes preparingthe stainless steel press plate for coating and coating the stainlesssteel press plate with a diboride doped with 1%-5% by weight aluminum(Al) to produce a diboride-aluminum (diboride-Al) coating. The step ofcoating includes applying the diboride-aluminum coating to a stainlesssteel press plate using a magnetron sputter coating system.

It is also an object of the present invention to provide a methodwherein the diboride is titanium diboride (TiB₂).

It is another object of the present invention to provide a methodwherein the stainless steel press plate is a 410 stainless steel highgloss press plates.

It is a further object of the present invention to provide a methodwherein the stainless steel press plate is a 300 stainless steel pressplate, a 410 stainless steel press plate, a 420 stainless steel pressplate, a 630 stainless steel press plate, or a 633 stainless steel pressplate.

It is also an object of the present invention to provide a methodwherein the diboride-aluminum coating has a Vickers hardness of at least35 GPa.

It is another object of the present invention to provide a methodwherein the diboride-aluminum coating has a Vickers hardness of 46 GPa.

It is a further object of the present invention to provide a methodwherein the diboride-aluminum coating has a thickness of about 3microns.

It is also an object of the present invention to provide a methodwherein the step of coating includes doping the diboride with 2% byweight Al.

It is another object of the present invention to provide a methodwherein the step of coating includes applying the diboride-aluminumcoating at a substrate bias of 60-90 V and at temperature of 200° C.

It is a further object of the present invention to provide a methodwherein the diboride-aluminum coating has a minimum bond strength of 1.6kilogram force (kgf).

It is also an object of the present invention to provide a methodwherein the diboride-aluminum coating has a minimum bond strength of 1.8kgf.

It is another object of the present invention to provide a methodwherein the step of preparing the stainless steel press plate includescleaning a pressing side of the stainless steel press plate.

It is a further object of the present invention to provide a methodwherein the step of preparing the stainless steel press plate includesetching the pressing side of the stainless steel press plate.

It is also an object of the present invention to provide a methodwherein the step of preparing the stainless steel press plate includesapplying a layer of titanium directly onto the pressing side of thestainless steel press plate

It is another object of the present invention to provide a methodwherein the step of coating includes applying multiple layers of thediboride-aluminum coating.

It is a further object of the present invention to provide a methodwherein the diboride-aluminum coating is applied in a two-stage processcomposed of a gradient based diboride-aluminum coating layer and toptitanium diboride-aluminum coating layer.

It is also an object of the present invention to provide a methodwherein the gradient based diboride-aluminum coating layer is 600 nm inthickness.

It is another object of the present invention to provide a methodwherein the top titanium diboride-aluminum coating layer is 1,240 nm inthickness.

It is further an object of the present invention to provide a coatedstainless steel press plate manufactured in according with the methoddescribed above.

Other objects and advantages of the present invention will becomeapparent from the following detailed description when viewed inconjunction with the accompanying drawings, which set forth certainembodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic of the present coated press plates used in themanufacture of high pressure decorative laminate.

FIG. 2 is a schematic of an embodiment of a coated press plate inaccordance with the present invention.

FIG. 3 is a schematic of a magnetron sputter coating system for use inaccordance with the present invention.

FIGS. 4 to 25 represent test results generated in accordance withExample 1 as discussed below.

FIG. 26 is a schematic of layered coatings in accordance with Example 2.

FIG. 27 is a schematic of alternative layered coatings in accordancewith Example 2.

FIGS. 28 to 31 represent test results generated in accordance withExample 2 as discussed below.

FIGS. 32 to 40 represent test results generated in accordance withExample 3 as discussed below.

FIGS. 41 to 47 represent test results generated in accordance withExample 4 as discussed below.

FIG. 48 is a schematic of an embodiment of a coated press plate inaccordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The detailed embodiments of the present invention are disclosed herein.It should be understood, however, that the disclosed embodiments aremerely exemplary of the invention, which may be embodied in variousforms. Therefore, the details disclosed herein are not to be interpretedas limiting, but merely as a basis for teaching one skilled in the arthow to make and/or use the invention.

In accordance with a preferred embodiment, and with reference to FIG. 1,stainless steel press plates 10 are coated with a diboride doped with1%-5% by weight aluminum (Al) 12 to produce a coated press plate 14 withan aluminum doped diboride-aluminum (diboride-aluminum (Al)) coating 12used in the manufacture of high pressure decorative laminates. Inaccordance with the present invention, the hardness of diboride coatingsused in the manufacture of stainless steel press plates for theproduction of high pressure decorative laminates is enhanced by applyingthe diboride coating to a stainless steel press plate using a magnetronsputter coating system and simultaneously doping the diboride with 1%-5%aluminum (Al).

As those skilled in the art will appreciate, the stainless steel pressplates 10 used in accordance with the present invention are sized forthe manufacture of decorative laminate sheets and include parallel firstand second planar surfaces 10 a, 10 b. For example, press plates arecommonly made in a variety of sizes depending upon the specificapplication for which the plate is destined. For example, press platescurrently used come in 38 inch (96.52 cm), 50 inch (127 cm) and 62 inch(157.48 cm) widths, 7 foot (2.1336 m), 8 foot (2.4384 m), 10 foot (3.048m), and 12 foot (3.6576 m) lengths and 0.085 inch (0.2159 cm) to 0.250inch (0.635 cm) thicknesses. While specific dimensions are disclosedherein, the stainless steel press plates may take a variety of formswithout departing from the spirit of the present invention.

In accordance with the present invention, the diboride is titaniumdiboride (TiB₂), although it is appreciated it may be possible toachieve results similar to the claimed invention through the use ofother diborides known to those skilled in the art to achieve highhardness characteristics when applied to a stainless steel substrate.Titanium diboride is more commonly used commercially for coatingsurfaces than other diborides, because it can be sputter coated in amagnetron sputtering system at a higher deposition rate.

As for the press plates 10 used in accordance with the presentinvention, they are preferably 410 stainless steel high gloss pressplates, although those skilled in the art will appreciate that 300, 410,420, 630, and 633 stainless steel press plates have been coated(exhibiting the same enhancement in surface hardness regardless of thesubstrate) and used in the manufacture of decorative laminates. As such,it is appreciated a variety of stainless steel high gloss press platesmay be used within the spirit of the present invention. As for the 410stainless steel high gloss press plates, and as those skilled in the artwill appreciate, 410 stainless steel press plates are 12% chromiummartensitic stainless steel plates that can be heat treated to obtain awide range of mechanical properties. The alloy has good corrosionresistance along with high strength and hardness. By way of example, a410 stainless steel press plate in accordance with the present inventionhas the following composition: chromium 11.5%-13.5% by weight; nickel0.75% by weight; carbon 0.08%-0.15% by weight; manganese 1.0% by weight;phosphorus 0.04% by weight; sulfur 0.03% by weight; silicon 1.0% weight;and iron 83.53%-85.6% by weight.

The aluminum doped titanium diboride coating (TiB₂—Al coating) 12 of thepresent invention is applied on stainless steel press plates 10 used inthe production of high pressure laminates. The resulting coated pressplates 14 are fabricated with a hardness sufficient for pressing highpressure decorative laminate with 25-60 micron or larger aluminaparticles at the pressing surface 16 of the high pressure decorativelaminate 18 without being scratched. In accordance with the presentinvention, the TiB₂—Al coating 12 (which is also referenced as “TBA” inthe figures) when applied to a stainless steel press plate 10 in themanner described below has a Vickers hardness of at least 35 GPa, andpreferably 46 GPa. It has been found that a TiB₂—Al coating 12 of about3 microns in thickness has sufficient hardness to resist scratching byalumina particles on the pressing surface 16 of a high pressuredecorative laminate 18 during the manufacture of thereof. As will beexplained below in greater detail, such a TiB₂—Al coating 12 is achievedby doping the TiB₂ with Al at approximately 1%-5% by weight Al, andpreferably 2% by weight Al, with a substrate bias of 60-90 Volts (V) (asit has been found that use of a substrate bias level of 60-90 Vincreases film hardness) and at temperature of 200° C. In order toproduce such a thickness, a target power of 200 Watts (W)×2 for the TiB₂and 3-15 (preferably 5) W×1 for Al is preferred. It is also preferredthat a Ti base layer 22 be applied between the TiB₂—Al coating 12 andthe stainless steel press plate 10. Further, the TiB₂—Al coating 12 hasa minimum bond strength of 1.6 kilogram force (kgf) and preferably 1.8kgf as determined by a diamond stylus scratch tester.

In accordance with each of the examples presented below, bonding of theTiB₂—Al coating 12 to the stainless steel press plate 10 is enhanced bythoroughly cleaning the pressing side 20 (that is, the side of thestainless steel press plate 10 that is intended to face the highpressure decorative laminate 18 during the manufacture process and thatcorresponds to the first planar surface 10 a of the present stainlesssteel press plate 10) of the stainless steel press plate 10 beforeintroducing the pressing side 20 of the stainless steel press plate 10into a magnetron sputter coating system 100. Bonding is further enhancedby etching the pressing side 20 of the stainless steel press plate 10prior to applying the TiB₂—Al coating 12. Cleaning, anodic etching,cathodic etching and etching with radio frequency (RF) is accomplishedby methods known to those skilled in the use of a magnetron sputtercoating system. In accordance with one embodiment as shown withreference to FIG. 2, it has been found that a base layer of titanium 22applied directly onto the pressing side 20 of the stainless steel pressplate 10 before applying the TiB₂—Al coating 12 of this inventionfurther enhances the bonding of the TiB₂—Al coating 12. Improvingbonding by cleaning, etching and the use of an intermediate layerbetween the TiB₂—Al coating 12 and the stainless steel press plate 10are known to those skilled in the art of using magnetron sputter coatingsystems.

It will be appreciated by those skilled in the art that magnetronsputter coating systems are well known and the present invention employsa magnetron sputter coating system well known to those skilled in theart. With that in mind, and with reference to FIG. 3 and considering theoperating parameters discussed below, it should be appreciated, themagnetron sputter coating system 100 of the present invention employs 3applicators 102, 104, 106, wherein two applicators 102, 104 are used inapplying TiB₂ and the other applicator 106 is used in applying the Al.This arrangement is designated below where the Targets are identified as“TiB₂×2, Al×1.”

Example 1

A TiB₂—Al coating was applied via the magnetron sputtering system inaccordance with the following conditions (Table 1) with Target Power(DC) for the Al varied to 3 W, 5 W, 7 W, 10 W, 15 W, 20 W, 25 W, 50 W,100 W, 150 W and 200 W:

TABLE 1 Substrate (Sub.) Silicon (Si)(100), Stainless Steel (SS) TargetsTiB₂ × 2, Al × 1 Target power (DC) TiB₂: 200 W × 2 Al: 3 W, 5 W, 7 W, 10W, 15 W, 20 W, 25 W, 50 W, 100 W, 150 W, 200 W Substrate bias (RF) −60 Vdc Working Pressure (8 × 10⁻³ torr) Reactive gas Ar (40 sccm (standardcubic centimeter per minute)) Deposition Time 2 hrs SubstrateTemperature 200° C.

As the results of FIGS. 4 and 5 show, the variation of Target powerresults in an Al percentage ranging from 1% to 40%. As discussed herein,preferred Al content is 1%-5% by weight, preferably 2%. Complete resultsgathered from this example are shown in FIGS. 4 to 25.

Example 2

A TiB₂—Al coating was applied via the magnetron sputtering system inaccordance with the following conditions (Table 2) with the gradientlayers varied. In particular, a Ti base layer was applied (for example,a base layer having a thickness of 300 nm) and a TiB₂—Al coating wasapplied at a target power of 5 W (to a thickness of 1240 nm) (see FIG.26). In addition, a TiB₂—Al coating was applied to the Ti base layerwith varying Al contents (see FIG. 27 where a TiB₂—Al coating withlayers of various compositions from its lowermost portion to itsuppermost portion). In particular, different Al contents were appliedusing applied target powers ranging from 5 W to 100 W (referenced asTBA5-TBA100, respectively, which stands for TiB₂—Al applied with targetpower of #W (which designation is used throughout the figures) toproduce layered coatings of different Al contents which were then testedas shown below.

TABLE 2 Substrate (Sub.) Silicon (Si)(100), Stainless Steel (SS) TargetTiB₂ × 2, Al × 1 Target power (DC) TiB₂: 200 W × 2 Al: 5 W (resulting ina TiB₂—Al coating with 2% Al) TiB₂: 200 W × 2 Al: 5 W-100 W SubstrateBias (RF) −60 V dc Working Pressure (8 × 10⁻³ torr) Reactive gas Ar (40sccm) Deposition time 2 hrs Substrate temperature 200° C.

The results of this example are shown in FIGS. 28 to 30. Based uponthese results it is apparent a Ti base layer between the TiB₂—Al coatingand the stainless steel press plate is desirable. While the inclusion ofthe Ti base layer may result in slightly reduced hardness, the enhancedadhesion characteristics when using a Ti base layer dictate thedesirability of the use of a Ti base layer in the manufacture of acoated press plate in accordance with the present invention.

Example 3

A TiB₂—Al coating was applied via the magnetron sputtering system inaccordance with the following conditions (Table 3) with the substratebias varied:

TABLE 3 Substrate (Sub.) Silicon (Si)(100), Stainless Steel (SS) TargetTiB₂ × 2, Al × 1 Target power (DC) TiB₂: 200 W × 2 Al: 5 W (resulting ina TiB₂—Al coating with 2% Al) Substrate bias (RF) Floating, −30 V, −60V, −90 V, −120 V Working pressure (8 × 10⁻³ torr) Reactive gas Ar (40sccm) Deposition time 2 hr Substrate Temperature 200° C. Substraterotation 5 rpm

The results of this example are shown in FIGS. 31 to 40, and support theconclusion to use a substrate bias of 60-90 V and at a temperature of200° C. in accordance with the fabrication of coated press plates inaccordance with the present invention.

Example 4

A TiB₂—Al coating was applied via the magnetron sputtering system inaccordance with the following conditions (Table 4) with the nitrogendoping at various levels:

TABLE 4 Substrate (Sub.) Silicon (Si)(100), Stainless Steel (SS) TargetTiB₂ × 2, Al × 1 Target power (DC) TiB₂: 200 W × 2 Al: 5 W (resulting ina TiB₂—Al coating with 2% Al) Substrate bias (RF) −60 V Working pressure(8 × 10⁻³ torr) Reactive gas Ar (40 sccm) N₂ (1, 2, 3, 4 sccm)Deposition time 2 hr Substrate temperature 200° C. Substrate rotation 5rpm

The results of this example are shown in FIGS. 41 to 47, and dictate theconclusion that nitrogen doping is not desirable when fabricating coatedpress plates in accordance with the present invention.

Based upon the results of Examples 1-4, the following preferredcriteria, as shown with reference to FIG. 48, for the application of theTiB₂—Al coating 12 have been established. First, the stainless steelpress plate 10 (preferably, composed high gloss 410 stainless steel) isprepared for the application of the TiB₂—Al coating 12. The pressingside 20 of the stainless steel press plate 10, that is, the side of thepress plate 10 to which the TiB₂—Al coating 12 is to be applied, isthoroughly cleaned and etched. Thereafter, a base layer of titanium 22,preferably with a thickness of 300 nm is applied directly onto thepressing side 20 of the stainless steel press plate 10 via the magnetronsputtering system 100.

The TiB₂—Al coating 12 is then applied. The TiB₂—Al coating 12 isapplied in a two-stage process composed of a gradient based TiB₂—Alcoating layer 12 a and top TiB₂—Al coating layer 12 b. The gradientbased TiB₂—Al coating layer 12 a is preferably 600 nm in thickness. Thetarget power of 200 W×2 for the TiB₂ is used in conjunction with asequentially increased target power of 5 W×1, 7 W×1& 10 W×1 for the Al.As such, the gradient based TiB₂—Al coating layer 12 a will have a 200nm thickness layer of TiB₂—Al 12 a′ applied at a target power of 200 W×2for the TiB₇ and a target power of 5 W×1 for the Al, a 200 nm thicknesslayer of TiB₂—Al 12 a″ applied at a target power of 200 W×2 for the TiB₂and a target power of 7 W×1 for the Al, a 200 nm thickness layer ofTiB₂—Al 12 a′″ applied at a target power of 200 W×2 for the TiB₂ and atarget power of 10 W×1 for the Al, The TiB₂—Al coating layer 12 a ispreferably applied with a substrate bias of 60-90 V and at a temperatureof 200° C.

The top TiB₂—Al coating layer 12 b is preferably 1,240 nm in thickness.The top TiB₂—Al coating layer 12 b is applied at a target power of 200W×2 for the TiB₂ and a target power of 5 W×1 for the Al to product a topTiB₂—Al coating layer 12 b with 2%-3% by weight Al. The top TiB₂—Alcoating layer 12 b is preferably applied with a substrate bias of 60-90V and at a temperature of 200° C.

While high hardness is achieved it is found that poor adhesion for theTiB₂—Al coating may be encountered. In deciding upon a desired hardness,and ultimately ranges for the operating parameters discussed above, itshould be appreciated that hardness must be balanced with the desire toprotect the press plate from protection against grit, which has aVickers hardness of at least 1,200 HV (11.77 GPa), and is preferably1800 HV (17.65 GPa) to 2000 HV (19.61 GPa), contained in high pressurelaminates being pressed as well as adhesion of the coating to thesubstrate wherein adhesion is known to increase when the coating issofter and thinner.

Enhanced adhesion is achieved by optimizing film crystallinity andpreferred orientation, reducing grain sizes, and providing solidsolution induced film compressive stress. As the examples abovedemonstrate, doping a few percent of Al in TiB₂—Al reduces grain size(FESEM (Field Emission Scanning Electron Microscope) and XRD (FWHM (Fullwidth at half maximum)), enhance TiB₂ (001) texture, Al atoms substituteTi or B to form solid solution, and increases film compressive stress.It was found that approximately 2% Al in TiB₂ makes the hardest films of46 GPa, but with the highest stress and poor adhesion, while at 9% to12% Al in TiB₂ the coating was found to have only moderate hardness of15 GPa to 30 GPa and better adhesion level. This is believed to resultfrom amorphous structure and low film stress (transition fromcompressive to tensile). It has further been found that a gradientTiB₂—Al film or intermediate metal Ti layer is effective to improve filmadhesion.

In addition, to those operating criteria disclosed above, it ispreferred that the magnetron sputtering system 100 be operated under thefollowing conditions: a working pressure of 8×10⁻³ torr and reactive gasof Ar (40 sccm). With regard to the scan rate, it is appreciated thescan rate when will be determined so as to curtail temperature gradientwithin the substrate.

While the preferred embodiments have been shown and described, it willbe understood that there is no intent to limit the invention by suchdisclosure, but rather, is intended to cover all modifications andalternate constructions falling within the spirit and scope of theinvention.

1. A method for coating stainless steel press plates, comprising:preparing the stainless steel press plate for coating; coating thestainless steel press plate with a diboride doped with 1%-5% by weightaluminum to produce a diboride-aluminum coating, wherein the step ofcoating includes applying the diboride-aluminum coating to a stainlesssteel press plate using a magnetron sputter coating system.
 2. Themethod according to claim 1, wherein the diboride is titanium diboride.3. The method according to claim 1, wherein the stainless steel pressplate is a 410 stainless steel high gloss press plates.
 4. The methodaccording to claim 1, wherein the stainless steel press plate is a 300stainless steel press plate, a 410 stainless steel press plate, a 420stainless steel press plate, a 630 stainless steel press plate, or a 633stainless steel press plate.
 5. The method according to claim 1, whereinthe diboride-aluminum coating has a Vickers hardness of at least 35 GPa.6. The method according to claim 5, wherein the diboride-aluminumcoating has a Vickers hardness of 46 GPa.
 7. The method according toclaim 1, wherein the diboride-aluminum coating has a thickness of about3 microns.
 8. The method according to claim 1, wherein the step ofcoating includes doping the diboride with 2% by weight aluminum.
 9. Themethod according to claim 8, wherein the step of coating includesapplying the diboride-aluminum coating at a substrate bias of 60-90 Vand at temperature of 200° C.
 10. The method according to claim 1,wherein the diboride-aluminum coating has a minimum bond strength of 1.6kilogram force.
 11. The method according to claim 10, wherein thediboride-aluminum coating has a minimum bond strength of 1.8 kilogramforce.
 12. The method according to claim 1, wherein the step ofpreparing the stainless steel press plate includes cleaning a pressingside of the stainless steel press plate.
 13. The method according toclaim 12, wherein the step of preparing the stainless steel press plateincludes etching the pressing side of the stainless steel press plate.14. The method according to claim 12, wherein the step of preparing thestainless steel press plate includes applying a layer of titaniumdirectly onto the pressing side of the stainless steel press plate. 15.The method according to claim 1, wherein the step of coating includesapplying multiple layers of the diboride-aluminum coating.
 16. Themethod according to claim 1, wherein the diboride-aluminum coating isapplied in a two-stage process composed of a gradient baseddiboride-aluminum coating layer and a top titanium diboride-aluminumcoating layer.
 17. The method according to claim 16, wherein thegradient based diboride-Al coating layer is 600 nm in thickness.
 18. Themethod according to claim 17, wherein the top diboride-aluminum coatinglayer is 1,240 nm in thickness.
 19. A coated stainless steel press platemanufactured in according with the method comprising: preparing thestainless steel press plate for coating; coating the stainless steelpress plate with a diboride doped with 1%-5% by weight aluminum toproduce a diboride-aluminum coating, wherein the step of coatingincludes applying the diboride-aluminum coating to a stainless steelpress plate using a magnetron sputter coating system.